A visual field test is used to help diagnose ocular disorders such as glaucoma and optic nerve diseases, as well as detect the presence and location of any brain tumors.
For a visual field test, the patient puts a patch over one eye to test the eyes individually. Once aligned with a fixation target, the patient clicks a button whenever they see a flash of light. Some flashes are brighter than others, used to test the sensitivity of the back of the eye, the retina. At some points, the patient cannot see a flash, and this is called a blind spot. Everyone has at least one blind spot: where the optic nerve meets the eye. If the patient has glaucoma or another eye disease, there may be more blind spots, or a loss of peripheral vision.
Used in conjunction with an OCT scan and other non-invasive tests, it allows the doctor to accurately diagnose ocular diseases.